Storage tank, as the name implies, is a container for storing articles, which is mainly used for storing food or moisture-proof articles. An ordinary storage tank can achieve the fresh keeping effect so long as food storage fresh keeping is defined as good container sealing performance. In fact, although an ordinary fresh keeping box has sealing characteristics, oxygen still exists in the box, while oxygen is just one of the key factors about whether fresh keeping is achieved.
To improve the fresh keeping effect of the storage tank, a vacuum-pumping mode can be adopted, to prevent oxygen from coming into contact with food, thereby achieving the purpose of prolonging the fresh keeping period of food. However, in the prior art, after vacuum-pumping is performed on the storage tank utilizing a vacuum-pumping machine, as time goes on, especially when sealing is poor, it is easy for air to enter the storage tank so that the fresh keeping function of the storage tank is destroyed.